Coolant leak back of engine.

Longun · 01-22-2015, 08:45 AM

Hi All, I've got a 2006 330d M57 Engined E90.

I've got a coolant leak somewhere near the back of the engine and I can see some small amounts of coolant dripping off near the gearbox. I can't for the life of me see what hose, or even figure out, what hoses are at the back of the engine that could leak.

I'm having to top up around 1L per week so its not a big leak but needs sorting.

Anyone know what hoses are at the back of the engine? Its not the heater hoses as they are visible on the bulk head and clean. This appears to be coming from a awkward spot at the rear that isn't very visible from above or below!

Appreciate any pointers

Puerto Rican 335d · 01-22-2015, 09:28 AM

check your engine oil first if its brownish color you hv some kind of leak in the engine if otherwise its not get under the car and trace it. Good luck amigo

Longun · 01-22-2015, 10:24 AM

Cheer for the pointer. No signs of HG issues. Very rare on the Derv engines. Temps all normal circa 90c and system not pressurising.

I can smell the coolant and see it on the under tray so is leaking from the back of the block somewhere. Must be a hose but I can't see one. Need to get a few more things out the way I think.

Puerto Rican 335d · 01-22-2015, 12:53 PM

congrats its a leak now look for it before it leaves you walking

BB_cuda · 01-22-2015, 03:27 PM

Put ultraviolet dye in coolant and look at it with a black light bulb. You will need to look quickly before the dye gets everywhere. By looking quickly you should be able to pin point the source. You may need to have it up on a lift with engine running and lower covers off.

I've traced power steering leak on different make that was very deceptive as it was on low pressure side

Longun · 01-22-2015, 03:55 PM

Quote:

Originally Posted by Puerto Rican 335d

congrats its a leak now look for it before it leaves you walking

I am, but I can't see where its coming from. Hence wondering if anyone knew what hoses, or parts of the coolant system exist around the rear of the engine, maybe near the starter. Hard to see where its coming from as its a small leak.

So front and middle under trays removed so I can see whats happening, removed the middle as it looked like it'd get torn off without the front one in place, left the two side ones.

I can visibly see coolant stains on the sump. But I'm still at a loss where its coming from.

https://www.dropbox.com/s/kukt92hzxs...20.36.jpg?dl=0

https://www.dropbox.com/s/2coqxpkgyy...20.41.jpg?dl=0

Also can see some coolant here:

https://www.dropbox.com/s/7gh6mg8gfc...22.55.jpg?dl=0

Removed undertrays. Fingers crossed things don't get too dirty before I refit them.

https://www.dropbox.com/s/flgpdzlzvd...20.07.jpg?dl=0

Longun · 01-22-2015, 03:56 PM

Quote:

Originally Posted by BB_cuda

Put ultraviolet dye in coolant and look at it with a black light bulb. You will need to look quickly before the dye gets everywhere. By looking quickly you should be able to pin point the source. You may need to have it up on a lift with engine running and lower covers off.

I've traced power steering leak on different make that was very deceptive as it was on low pressure side

Top idea. Will see if I can some on the net. Its a small leak so might be handy to try and trace it back. As above all under trays are off to aid spotting this damn leak!

Puerto Rican 335d · 01-23-2015, 08:13 AM

Long try to narrow it it could be leaking from somewhere else and trickling down

BB_cuda · 01-23-2015, 09:56 AM

Yep, PR is right. Leaks are deceptive. This is especially true if it takes a while to appear on oil pan like your photos show

Longun · 12-15-2018, 02:38 PM

Just to update this thread for a giggle. I never did find the leak. It's still leaking almost 4 years later. Every now and again it seems to stop for a few months then start again

Even done a couple of track days

01-22-2015, 08:45 AM	#1
Longun New Member 4 Rep 22 Posts Drives: F10 M5 2012 Join Date: Mar 2014 Location: Gloucestershire, UK. iTrader: (0)	Coolant leak back of engine. Hi All, I've got a 2006 330d M57 Engined E90. I've got a coolant leak somewhere near the back of the engine and I can see some small amounts of coolant dripping off near the gearbox. I can't for the life of me see what hose, or even figure out, what hoses are at the back of the engine that could leak. I'm having to top up around 1L per week so its not a big leak but needs sorting. Anyone know what hoses are at the back of the engine? Its not the heater hoses as they are visible on the bulk head and clean. This appears to be coming from a awkward spot at the rear that isn't very visible from above or below! Appreciate any pointers
	Appreciate 0 Tweet Quote

01-22-2015, 09:28 AM	#2
Puerto Rican 335d Brigadier General 236 Rep 3,488 Posts Drives: Montego Blue 335d Join Date: Jun 2011 Location: Puerto Rico(Dominican Republic 03/2017) iTrader: (0)	check your engine oil first if its brownish color you hv some kind of leak in the engine if otherwise its not get under the car and trace it. Good luck amigo __________________ RENNtech Flash(Lenny Wu)/WAGNER IC Enkei Rajin 18"/Execuhitch Hitch/Koni FSD Soft Ride Bike Rack/Brava Synthetic Motor Oil(Made in Puerto Rico)/Meth(in the works)/CBU done w Andrew EGR Race Pipe (whoa! what an animal it is now)
	Appreciate 0 Quote

01-22-2015, 10:24 AM	#3
Longun New Member 4 Rep 22 Posts Drives: F10 M5 2012 Join Date: Mar 2014 Location: Gloucestershire, UK. iTrader: (0)	Cheer for the pointer. No signs of HG issues. Very rare on the Derv engines. Temps all normal circa 90c and system not pressurising. I can smell the coolant and see it on the under tray so is leaking from the back of the block somewhere. Must be a hose but I can't see one. Need to get a few more things out the way I think.
	Appreciate 0 Quote

01-22-2015, 12:53 PM	#4
Puerto Rican 335d Brigadier General 236 Rep 3,488 Posts Drives: Montego Blue 335d Join Date: Jun 2011 Location: Puerto Rico(Dominican Republic 03/2017) iTrader: (0)	congrats its a leak now look for it before it leaves you walking __________________ RENNtech Flash(Lenny Wu)/WAGNER IC Enkei Rajin 18"/Execuhitch Hitch/Koni FSD Soft Ride Bike Rack/Brava Synthetic Motor Oil(Made in Puerto Rico)/Meth(in the works)/CBU done w Andrew EGR Race Pipe (whoa! what an animal it is now)
	Appreciate 0 Quote

01-22-2015, 03:27 PM	#5
BB_cuda Brigadier General 796 Rep 3,572 Posts Drives: 2011 335D Msport, 2013 X5D Join Date: Nov 2011 Location: Clear Lake, Texas iTrader: (0)	Put ultraviolet dye in coolant and look at it with a black light bulb. You will need to look quickly before the dye gets everywhere. By looking quickly you should be able to pin point the source. You may need to have it up on a lift with engine running and lower covers off. I've traced power steering leak on different make that was very deceptive as it was on low pressure side
	Appreciate 0 Quote

01-23-2015, 08:13 AM	#8
Puerto Rican 335d Brigadier General 236 Rep 3,488 Posts Drives: Montego Blue 335d Join Date: Jun 2011 Location: Puerto Rico(Dominican Republic 03/2017) iTrader: (0)	Long try to narrow it it could be leaking from somewhere else and trickling down __________________ RENNtech Flash(Lenny Wu)/WAGNER IC Enkei Rajin 18"/Execuhitch Hitch/Koni FSD Soft Ride Bike Rack/Brava Synthetic Motor Oil(Made in Puerto Rico)/Meth(in the works)/CBU done w Andrew EGR Race Pipe (whoa! what an animal it is now)
	Appreciate 0 Quote

01-23-2015, 09:56 AM	#9
BB_cuda Brigadier General 796 Rep 3,572 Posts Drives: 2011 335D Msport, 2013 X5D Join Date: Nov 2011 Location: Clear Lake, Texas iTrader: (0)	Yep, PR is right. Leaks are deceptive. This is especially true if it takes a while to appear on oil pan like your photos show
	Appreciate 0 Quote

12-15-2018, 02:38 PM	#10
Longun New Member 4 Rep 22 Posts Drives: F10 M5 2012 Join Date: Mar 2014 Location: Gloucestershire, UK. iTrader: (0)	Just to update this thread for a giggle. I never did find the leak. It's still leaking almost 4 years later. Every now and again it seems to stop for a few months then start again Even done a couple of track days
	Appreciate 0 Quote